12.5" F5.16 ETT (EasyTransport Telescope).

The ETT differs from the standard configuration in that the struts are one-half length and an intermediate ring is added which provides rigidity and stability to the assembly.  For example, instead of using 3 60-inch struts in the telescope design, the ETT incorporates six 30-inch struts. An Easy Transport Telescope!
In the smaller sizes, 8" and 10" Newtonians, these telescopes will break down to a size suitable for airline transport as baggage. The larger telescopes don't meet that requirement, but still make the telescope much easier to transport, setup and store.
This example is a 12.5" Transportable Telescope made for George in Show Low Arizona.  George sent me his mirror and mirror cell, spider/secondary and focuser. He had a pair of finder rings to be mounted as well.

The overall length of the struts are 59.5" long and the eyepiece stands at 64.5" when pointed at the zenith.  Each section of the struts is 29 1/4". The intermediate ring is .5" thick and is also made of furniture grade Baltic birch.

The footprint of the rocker box is 19"x21.5" and stands 16" all. The height of rocker box can vary. In this case, since George had a fairly heavy finder and a 1.5# eyepiece, I've put the altitude bearings a little higher on the OTA. A sliding counterweight will assist in the final balance of the telescope, when needed.

The scope was built and delivered in December 2008.


The 12.5" telescope from the rear. Here is the removable dew shield is installed. In this case, the mirror cell is a Kenneth Novak. I modified the cell, slightly, to allow a larger center opening to assist is cool-down of the mirror.
12.5" F5.16 ETT as seen from the front. The focuser baffle is in place. The entire telescope assembles and disassembles without the need for tools.
The ETT with the dew shield removed. The mirror cover is standard equipment and is in place whether the dew shield is installed or removed.  
Another view with the dew shield in place.  
Since the "travel struts" are 1/2-length, it is easy to use the bottom half of the strut when transporting the telescope. Here, the altitude bearings are left in place. The one-half strut length is 29 1/4".  
Simply remove the altitude bearings and nest the OTA assembly in the rocker box. The intermediate ring is at the bottom of the rocker box.
The assembly is just about complete. The sliding counterweight and finder rings are installed. I include a "finder" clamp regardless of the finder type. Many amateurs use a small, lightweight, red-dot zero-power finder.
The intermediate ring and focuser baffle fit nicely into the bottom of the rocker box for easy transport.

For more information about your requirements:
--Dennis Steele
--Tel: 650-315-6578 (anytime)
--Email: densteele@dobstuff.com

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